[请教]BIOS地址映射?

暴雪

原512K的ROM，现换了一个1M的ROM，windows下在 0xFFF0 0000~0xFFF7 FFFF 可以看到追加的512K的内容。
  W* L  v2 {% Z: Q0 {: S7 J/ r但在启动计算机时(BIOS没有初始化计算机），无法访问追加的512K的ROM。
1 {; B- O4 I) [2 d% {5 f" y6 f" k/ T- K(可以访问原512K的ROM 0xFFF8 0000~0xFFFF FFFF)
" n' H9 G% F! g% y8 ?
我的计算机用的是intel的ICH7南桥。
在手册上
FWH_SEL2—Firmware Hub Select 2 Register (LPC I/F—D31:F0)
FWH_70_IDSEL — R/W. IDSEL for two, 1-M Firmware Hub memory ranges.
The IDSEL programmed in this field addresses the following memory ranges:
FF70 0000h – FF7F FFFFh
8 D; o" {8 W# i) {FF30 0000h – FF3F FFFFh
7 q7 ^( [) q5 K% t在这里 IDSEL 如何理解。
) m, ?- P0 ]9 U& }0 O' `* qFWH_DEC_EN1—Firmware Hub Decode Enable Register
(LPC I/F—D31:F0)
FWH_70_EN — R/W. Enables decoding two 1-M Firmware Hub memory ranges.
0 = Disable.
1 = Enable the following ranges for the Firmware Hub
FF70 0000h – FF7F FFFFh
# E- x, \. E; Z# q# i1 lFF30 0000h – FF3F FFFFh
! {5 t' \7 K8 m) R9 t$ x0 d除了上面的数据区域，还有其它的数据区域控制ROM到内存地址的映射吗？
7 }) x2 l/ {, ^0 V* v
谢谢大家了！！！

xtdumpling

IDSEL是LPC spec的一个信号(Device Select),
This one clock field is used to indicate which of multiple Firmware components is being selected.
! a" x/ D* O6 T# |) I2 [The four bits transmitted over AD[3:0] during this clock are compared with values strapped onto
pins on the Firmware component. If there is a match, the Firmware component will continue to
decode the cycle to determine which bytes are requested on a read or which bytes to update on a
write. If there isn’t a match, the Firmware component may discard the rest of the cycle and go into
a standby power state.
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% _/ n" X! E1 E$ y3 @5 ^* @: Y详见LPC spec:
http://www.intel.com/design/chipsets/industry/25128901.pdf
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在ICH 7 中似乎就这几个吧(FWH_SEL1,FWH_SEL2,FWH_DEC_EN1,BIOS_CNTL),据我现在知道的.